N-Alkyl α-diazo-γ-butyrolactams, previously found to be unstable and to undergo unproductive dimerization to bishydrazones, were successfully converted immediately to various X–H insertion products with alcohols, aromatic amines and thiols via an in situ RhII-catalyzed reaction. With aliphatic amines or unreactive, sterically hindered anilines, the reactions tended to yield enamine adducts.
The only cyclic α-diazocarbonyl compound employed in the Büchner–Curtius–Schlotterbeck ring expansion of cyclic ketones to date was α-diazo-γ-butyrolactone. Encouraged by the recent success using α-diazo acetamides in related Tiffeneau–Demjanov type ring expansions, we extended this approach to various α-diazo-γ-butyrolactams, which produced, under BF3·OEt2-promoted conditions, spirocyclic seven-membered ketones. These findings substantially enhance the possibilities offered by cyclic α-diazocarbonyl compounds in constructing privileged spirocyclic scaffolds for drug design.
N-Alkyl a-diazo-g-butyrolactams previously found to be unstable and undergo unproductive dimerization to bis-hydrazones, were successfully converted immediately to various X-H insertion products with alcohols, aromatic amines and thiols via an in situ RhII-catalyzed reaction. With aliphatic amines or unreactive, sterically hindered anilines, the reaction tends to yield enamine adducts.
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